I'm almost finished levelling my Mage, who is Tailoring/Engineering. I've just put some Synapse Springs on my gloves, and thrown together an exact copy of the macro I used to use for them on my old Mage - which I haven't played since about last July. This is the macro:

The old macros were identical apart from using Frostbolt or Arcane Blast, and I know they worked. Now, though, when I'm spamming the spell and the gloves come off cooldown, it fails to cast almost every time, saying that another action is in progress.

Is this something to do with the custom lag tolerance setting? Is the queuing of my next Fireball while the current one is casting preventing the gloves from activating?

They're just silent .wav files that will overwrite the default ones. HolyA is the default fizzle sound for most any non-specific spell, FrostA is in there for Icy Veins, I think. Try it with that, see if perhaps all the scripting is messing it up.